Refrigeration of oyster shellstock: Conditions which minimize the outgrowth of Vibrio vulnificus

The multiplication of Vibrio vulnificus in summer harvest oyster shellstock held without refrigeration was followed over a 14 h postharvest period. Mean (n = 7) increases were 0.75, 1.30, 1.74, and 1.94 log units at 3.5 h, 7 h, 10.5 h, and 14 h postharvest, respectively. Aerobic plate counts (spread plates on plate count agar [PCA] containing 1% NaCl, 25 degrees C) but not standard plate counts (pour plates, PCA, 35 degrees C) showed a similar trend in increase. Reducing the time oyster shellstock remains outside refrigeration can decrease consumer exposure to high numbers of V. vulnificus, but shellstock must be cooled immediately after harvest to eliminate postharvest growth of this bacterium.